Friday, June 04, 2004

Less is More: When it comes to Vitamin C, taking too much can accelerate arthritis, at least in guinea pigs:

"The guinea pig is the ideal animal in which to test this,' Kraus explained, 'because they require vitamin C in their diet, just like humans, and they get an osteoarthritis of their knees that looks very similar to the type of knee osteoarthritis that humans get.'

Arthritis specialists have long recommended that patients consume an adequate daily amount of vitamin C because the nutrient is both a potent antioxidant and a key player in the formation of joint cartilage. But would higher doses of the vitamin make bones even stronger?

Not so, Kraus reports. 'More is not better,' she said. 'We found that the more vitamin C given, the more osteoarthritis is apparent in the joints of these animals that are predisposed to getting osteoarthritis.'

Guinea pigs fed low doses of vitamin C showed the least signs of knee arthritis, Kraus said, but since they also tended to weigh much less than the medium- or high-dose animals, reductions in weight might explain that result.

Animals fed a medium dose of vitamin C -- roughly equivalent to the recommended daily allowance in humans -- had slightly more signs of knee damage. But it was the high-dose animals that fared worse, with obvious signs of arthritis and an increase of bony outcroppings on the knee called osteophytes or bone spurs.